Gas ranges which cook using the combustion of natural gas or the like are prized by chefs who value their fast response and high heat output. Such gas ranges may use gas valves which meter gas to individual burners according to rotation of the valve stem communicating with an internal valve mechanism. Control of the gas valves by a consumer is provided by rotation of a control knob fitting over an end of the valve stem as it passes through a console on the front of the range. By controlling the volume flow of gas to the burner, the output of the burner may be adjusted. Many modern gas ranges include electronic igniters that may be triggered by initial movement of the valve detected by a sensor switch to automatically ignite the gas at the burner.
Low heat ranges for simmering or the like are not always easily obtained with a gas range because low rates of gas flow are difficult to control to a steady level and/or low gas flow rates do not reliably support a flame. For this reason, high-end gas ranges may employ a strategy for low heat ranges in which heat output is controlled not by adjusting the continuous rate of gas flow but by pulsing the gas flow on and off according to a schedule to control an average treated gas flow producing the desired heat. Electrical igniters ignite the gas at the beginning of each pulse cycle.
This technique of heat control requires a rotational encoder attached to the gas valve to relay its rotational position by an electrical signal to a controller that may effect the desired pulse schedule turning the gas valve on and off and that may appropriately control the igniter. This rotary encoder, for example, may be a potentiometer having a rotating element through which the valve stem is threaded so that the rotating element turns with the valve stem and provides a variable voltage (or resistance) indicating the rotational position of the valve stem.
Assembly or replacement of the rotary encoder on the gas valve can be difficult, requiring installation or removal of the rotary encoder before the valve stem is inserted through a hole in the console and thus before the valve stem is securely positioned to the range. Early installation of the rotary encoder risks damage to the encoder during mechanical assembly of the valves to the manifold and gas piping of the range and prevents pre-assembly of the valves to a frame before they are identified to a particular range feature set.